The invention relates to an apparatus suitable for twisting a yarn. In another aspect, the invention relates to a method suitable for twisting a yarn. In still another aspect the invention relates to an apparatus and method suitable for twisting an as spun yarn.
The use of synthetic yarns presently dominates the textile industry. Although some natural fibers such as cotton and wool are still used today, the majority of yarns used to produce clothing, carpeting, upholstery material and other textile goods are primarily synthetic yarns. In order for synthetic yarns to resemble yarns made from natural fibers, it is necessary to texture or bulk the synthetic yarns. Texturing synthetic yarns in order that such yarns when made into fabrics will have the hand and feel of fabrics made from natural staple yarns is well known in the art. The various texturing processes used to texture synthetic yarns also employ a variety of feed yarns. For example, a feed yarn can be drawn, partially drawn or undrawn and a feed yarn can be twisted or entangled to bind the filaments in the yarn closer together because a yarn that is not twisted or entangled often has filaments that become separated from the yarn that can snag and break during the various processing steps. Also packages of feed yarn should be used in a size or weight best suited for the particular process used. Some of the more commonly employed texturing processes use a feed yarn that has been twisted and drawn. To produce such a feed yarn, a draw-twist machine is frequently used. Such a machine, which is well known in the art, draws an as spun yarn and then twists the drawn yarn during windup by feeding the yarn to a rotating vertically mounted takeup bobbin through a rotatable "flyer" driven only by the angular momentum of the yarn. Although this type of machine works very well and is widely used, the packages of draw-twisted yarn that can be produced on such machines are relatively small because the windup bobbin itself must be rotated. In some texturing processes where large packages of feed yarn are desirable it is necessary to splice and recone the draw-twisted yarn to make larger feed yarn packages.
The problem of package size along with other disadvantages of the draw-twist process are overcome by use of the twist-draw process, that is, where the as spun yarn is twisted by a 2-for-1 twister and then drawn. In such a process the yarn is twisted prior to winding so that the types of winders employed are capable of winding much larger packages of yarn as compared to the takeup bobbin used on draw-twist machines. Although the twist-draw process solves problems that are encountered with draw-twist processes, the twist-draw process itself has some problems and one of the more difficult problems with the twist-draw process has been in the control of the tension of the yarn passed to the twisting spindle on the 2-for-1 twister. Prior to the present invention the tension devices used on 2-for-1 twisters employed pinch points that trapped the yarn between two surfaces. However, the use of 2-for-1 twisters having tension devices employing pinch points to regulate the tension in the yarn generally has been unsatisfactory because of filament breakage; thus there is a need for a 2-for- 1 twister that can twist an as spun yarn with the elimination of or at least only a minimum number of broken filaments.
An object of the invention is a 2-for-1 twister.
Another object of the invention is an apparatus suitable for twisting an as spun yarn with a minimum of filament breakage.
Another object of the invention is twisting yarn.
Still another object of the invention is twisting an as spun yarn with minimum filament breakage.